Natural Plant Extracts and Microbial Antagonists to Control Fungal Pathogens and Improve the Productivity of Zucchini (Cucurbita pepo L.) In Vitro and in Greenhouse

Abstract

Background: Natural plant extracts and microbial antagonists have the potential for use in increasing the fungal resistance and productivity of horticulture plants. Methods: The purpose of this study was to evaluate the ability of both natural plant extracts and microbial antagonists as a biotical control of some fungal pathogens, i.e., Fusarium ssp., Exserohilum ssp. and Nigrospora ssp., along with improving the growth and productivity performance of zucchini under greenhouse conditions. Eucalyptus camaldulensis leaf extract (LE), Citrus sinensis LE, Ficus benghalensis fruit extract (FE), and two microbial antagonists Pseudomonas fluorescens (accession no. MW647093) and Trichoderma viride (accession no. MW647090) were tested under in vitro and in vivo conditions. Through morphological characteristics and the internal transcribed spacer (ITS) region, Fusarium solani (accession no. MW947256), F. oxysporum (accession no. MW947254), Exserohilum rostratum (accession no. MW947255), and Nigrospora lacticolonia (accession no. MW947253) were identified. HPLC analysis was used for the identification of phenolic compounds (PCs) and flavonoid compounds (FCs) in the extracts. Results: The highest inhibition percentage of fungal growth (IPFG) against F. oxysporum was obtained with P. fluorescens, T. viride, and E. camaldulensis LE (4000 mg/L); F. solani with P. fluorescens, T. viride, and C. sinensis LE (4000 mg/L); Exserohilum rostratum with P. fluorescens, Ficus benghalensis FE (4000 mg/L) and E. camaldulensis LE (4000 mg/L), and N. lacticolonia with P. fluorescens. Using HPLC analysis, the abundant PCs in E. camaldulensis LE were pyrogallol, and caffeic acid, those in C. sinensis LE were syringic acid and ferulic acid, and those in F. benghalensis FE were gallic acid and syringic acid. In addition, the abundant FCs in E. camaldulensis LE were kaempferol, and naringin, those in C. sinensis LE were hesperidin and quercetin, and those in F. benghalensis FE were kaempferol and quercetin. Under greenhouse experiments, T. viride and E. camaldulensis LE (4000 mg/L) followed by P. fluorescens + T. viride treatments gave the best results of zucchini plants in terms of leaf area, fruits number per plant, yield per plant, and total yield (marketable and non-marketable). Conclusions: Plant extracts and bioagents can be used to control some zucchini fungal pathogens and increase the productivity performance of zucchini plants.

Photosynthetic Pigments and Biochemical Response of Zucchini (Cucurbita pepo L.) to Plant-Derived Extracts, Microbial, and Potassium Silicate as Biostimulants Under Greenhouse Conditions

“…Plant growth, quality, tolerance to abiotic and biotic stresses, photosynthesis, and using nutrients, fertilizers, and water are able to be enhanced by plant-derived biostimulants (PDBs) by modulating plant biochemical, molecular, and physiological processes (Rouphael and Colla, 2020b ; Godlewska et al, 2021 ; Mosa et al, 2021b ). Our previous work (Hassan et al, 2021 ) showed that the most abundant phenolic compounds in Eucalyptus camaldulensis LE were pyrogallol, caffeic acid, and p -coumaric acid, in Citrus sinensis LE were syringic and ferulic acids, and in Ficus benghalensis were gallic, p-coumaric, and syringic acids.…”

“…It can be said that biological stimulants have a positive effect on a number of chemical properties of fruits and vegetables. It is evident that the use of several types of PDBs has potential effects on the development and quality of several plant species, for example, tomato (Souri and Bakhtiarizade, 2019 ), rocket (Di Mola et al, 2019 ), and zucchini (Hassan et al, 2021 ).…”

“…The current experiments were performed to study the effect of plant extracts, K 2 SiO 3 , and microbial inoculation with Trichoderma viride (10 6 spore/ml) and Pseudomonas fluorescens (10 8 CFU/ml) as biostimulants on the growth, productivity, and bioactive of zucchini fruit that is grown in greenhouse conditions. Extracts were prepared from Eucalyptus camaldulensis leaves, Citrus sinensis leaves, and Ficus benghalensis fruits at the concentration of 4,000 mg/L as recommended in our previous work (Hassan et al, 2021 ).…”

“…Phenolic compounds were separated by employing a mobile gradient phase of water/acetonitrile/glacial acetic acid (980/20/5, v/v/v, pH 2.68) and acetonitrile/glacial acetic acid (1,000/5, v/v) with a flow rate of 1 ml/min and detected at 325 nm. All chemical standards (HPLC grade) were purchased from Sigma-Aldrich (St. Louis, MO, USA) (Hassan et al, 2021 ).…”

Pomegranate trees quality under drought conditions using potassium silicate, nanosilver, and selenium spray with valorization of peels as fungicide extracts

“…Chromatograms were obtained and analyzed using the Agilent ChemStation. The separation and identification conditions ca be found in the previous work 58 .…”